Production of alcohols



United States Patent Ctiicc 2,724,729 Patented Nov. 22, 1955 PRODUCTION OF ALCOHOLS Eugene J. Lorand, Wilmington, Del., assiguor to Hercules Powder Company, Wilmington, Del., a corporation of Delaware No Drawing. Application December 29, 1951,

Serial No. 264,236

4 Claims. (Cl. 260-618) This invention relates to the preparation of tertiary alcohols and, more particularly, to a process involving Also, the reducing agents of the art, in general, have not been capable of use in alkaline medium. The latter fact has been particularly disadvantageous when it has been desired to reduce hydroperoxides which were unstable in acid medium. 1

It has now been found that improved yields of apt-dialkylarylmethyl alcohols of the formula ROH, wherein.

R is a radical of the formula where R1 and R2 represent alkyl groups and Ar represents an aryl or substituted aryl group, may be obtained by treating a hydroperoxide of the formula ROOH (where R is the same as above) with a hydrocarbon of the formula Rl-I (where R is the same as above) underanhydrous conditions in the presence of a strong base soluble in the reaction mixture.

Tertiary alcohols are produced in accordance with this invention, forexample, by treating a mixture of a tertiary hydroperoxide and its corresponding hydrocarbon, for example, .a,a-dimethylbenzyl hydroperoxide and cumene, under anhydrous conditions with abase such as sodium methylate at a temperature of from about 60 C. to 200 C. By means of the reaction between these reagents there is produced u,a-dimethylbenzyl alcohol in quantities which substantially exceed the theoretical yield based upon the amount of hydroperoxide utilized. 1

The following examples constitute specific embodiments of the invention. All parts are on the basis of parts by weight.

Example 1 A reaction vessel fitted with a stirrer, a thermometer, a reflux condenser and an inlet tube for the introduction of nitrogen was charged with 37.5 parts cumene of greater than 99% purity and 12.5 parts of a cumene oxidation reaction mixture obtained by the air oxidation of cumene and containing 96.7% a,a-dimethy1benzyl hydroperoxide. The reaction charge was covered with a nitrogen atmosphere and 1.5 parts of phenyl lithium added over a period of 45 minutes while agitating the reaction mixture at 100 C. The reaction product was filtered to remove a precipitate. The filtrate was found to contain a,a-dimethylbenzyl alcohol in an amount representing a 2 yield of 135% based upon the weight of hydroperoxide decomposed.

Example 2 Using the apparatus of Example 1, 45 parts cumene of greater than 99% purity and 15 parts of a cumene oxidation reaction mixture obtained by the air oxidation of cumene and containing 97.6% a,a-dimethylbenzyl hydroperoxide were charged to a reaction vessel and covered with nitrogen. To the reaction mixture was added 1.5 parts of commercial 95% sodium methylate, over a period of 0.7 hour while agitating the reaction mixtureat 100 C. The reaction product was filtered to remove a brown gelatinous precipitate.

resented a yield of 130% based upon the weight of hydroperoxide decomposed.

The process of this inventioin is applicable to any tertiary hydroperoxide of the formula R1 Ar-tL-OOH l tz I in which R1 and R2 are alkyl groups and Ar is an aryl or substituted aryl group. The hydroperoxides of this class may be described generally as a,u-dialkylarylmethyl hydroperoxides and may be prepared by the oxidation a 40% based upon the weight of hydroperoxide, althoughof a,a-dialkylarylmethanes having the structural formula R1 Ar--('JH in which R1, R2, and Ar have the same meanings as above. Thus, cumene, p-cyrnene, p-diisopropylbenzene, and isopropylnaphthalene may be oxidized to a,m-dimethylbenzyl-, a,a-dimethyl-p-methylbenzyl-, a,a-dimethyl-p-isopropylbenzyl-, and a,a-dimethylnaphthylhydroperoxides, respectively. In the case of p-diisopropylbenzene there may also be obtained a,ot,a',u -tetramethyl-pxylylene dihydroperoxide. The oxidation may be carried out in the liquid phase utilizing air or molecular oxygen as the oxidizing agents. A preferred method of preparing these hydroperoxides involves the liquid phase oxidation of the alkyl-substituted aromatic organic compounds having the above structural formula by passing an oxygen-containing gas through the compounds at a temperature between about 50 C. and about C. in the presence of an aqueous alkali. The concentration of the alkali may be between about 0.01% and about it is preferable to use concentrations of about 1%to about 15%. Vigorous agitation is desirable during the oxidation reaction. i

The a,et-dialkylarylmethyl hydroperoxides which are caused to react with a,a-dialkylarylmethanes in accordance with this invention for the production of the cor responding tertiary alcohols may have the same or different structure from that of the a,a-dialkylarylmethanes. The examples have shown the reaction in which the a,a-dialkylarylmethyl radical is the same for both the hyd roperoxide and the hydrocarbon. The reaction may also be carried out between hydroperoxides and hydrocarbons having dissimilar radicals, for instance, a,a-dimethylp-rnethylbenzyl hydroperoxide may be contacted benzyl alcohol and a, x-dimethylbenzyl alcohol, and the net result of the reaction is that both hydroperoxide and hydrocarbon are converted to the corresponding enadialkylarylmethyl alcohol.

The filtrate was found to contain 35% a,a-dimethylbenzyl alcohol, which rep The formulas '2 have been applied broadly to the liydropcroxide, hydrocarbon, and alcohol concerned in the present invention. In these general formulas Ar represents an aryl or subsutured aryl group and includes aryl and alkaryl groups 7 derived from benzene, naphthalene, anthracene, phcnanthrone, and the like. The aryl group may be substituted with aI-kyl groups such as methyl, ethyl, propyl, isop'ropy'l, butyl, isobutyl, secondary butyl', tertiary butyl, etc., to give alkaryl groups, the same alkyl groups also being representative of R1 and R2 in the structural formula. R1 and R2 may be the same or ditierent. For example, compounds such as u,a-dimethylbenzyl-, mot-dimethyl-p-mcthylbenzyl-,- and a,a-dimethyl-pisopropylbenzyl-hydroperoxides may be treated with the corresponding hydrocarbons in accordance with this invention to produce the corresponding alcohols. Similarly dihydroperoxides such as a,a,a,a-tetramethyl-p-xylylene dihydroperoxide may be converted to a,u,a,a'-tetramethyl pfxylylenediol. Also, the aryl group may be substituted with nonhydrocarbon groups such as nitro, halogen, alkoxy, cyano, etc, groups as in the case of nitrophenyl, chlorophenyl, methoxypbenyl, cyanophenyl, nitronaphthyl, chloronaphthyl, methoxynaphthyl, cyanonaphthyl, etc.

The process of this invention may be carried out either with a purified hydrope'roxide and a pure hydrocarbon or it may be carried out using a partially oxidized hydrocarbon rich in hydroperoxides; When desirable, the hydroperoxide may be separated from the other constituents of the reaction mixture by, for example, fractional distillation at very low pressures, of the order of 0.01 to 1.0 mmJ'sq; cm., the hydroperoxides having higher boiling points than the related hydrocarbon, alcohol, and ketone. in certain instances the hydroperoxide also may be separated from the oxidation reaction mixture by crystallization, which may be facilitated by first distilling off part of the hydrocarbon.

The process of the present invention may be applied to a partially oxidized hydrocarbon with or without dilution (xirelatively pure hydroperoxide may be diluted with. hydrocarbon, When a partially oxidized hydro carbon is added to a hydrocarbon containing a strong mixture added to fresh hydrocarbon in the presence of catalyst.

The present process of reacting an a-dialkyl arylmethyl hydroperoxide with an u,a-dialkyla.rylmethane in the presence of a strong base catalyst soluble in the reaction mixture gives a lower proportion of byproducts and a substantially greater yield of alcohol based on the hydroperoxide than any of the prior art processes.

The catalysts of this invention may be generally described as those materials which are known in the chemical art as strong bases and which are soluble in mixtures of the hydrop'eroxides and hydrocarbons of this invention. Thus, metal alkoxides such as sodium methylate, sodium ethylate, sodium propylate, and metal aryloxides such as sodium phenol'ate, etc., may be utilized, and also included within the class of compounds operable in this invention are metal alkyl compounds such as triphenylmethyl sodium, methyl sodium, etc., and metal aryl compounds such as phenyl lithium. The strong base is preferably utilized in powdered form, but may also be used in any other anhydrous condition. Concentration of base may vary from about 0.1% to about 40% based upon the weight of hydroperoxide, but it is preferred that about 2% to 15% base with respect to the weight, of the hydroperoxide be utilized.

The process of this invention is carried out under anhydrous conditions. It has been found that under conditions other than anhydrous the formation of by-products such as ketones is favored, thereby substantially reducing the eificiency of the process. The temperature of the reaction may be varied from about 60 to 200 C-, but temperatures of to C. are most desirable as resulting in the highest yields of alcohol with the, ieast attendant production of lay-products. Both batch and continuous operations may be utilized.

it is desirable from time to time to check the hydroperoxid'e content in the reaction mixture. This can be carried out utilizing the well-known iodine liberation method which involves removal of a sample of the reaction mixture from the reaction vessel and adding this sample to an acidified potassium iodide solution and noting the amount of iodine which is liberated. Upon completion of the reaction, the hydroperoxide content should not exceed a rather low limit which will vary depending upon the nature of the hydroperoxide, but generally falls within the range of (lto about 3%. Upon'cornp'letion of the reductionthe reaction mixture maybe worked up by well-known procedures.

The process in accordance with this invention provides an efiicient and economical means for the preparation of alcohols. It is particularly useful in those instances in which the alcohols have been difiicultly obtained by other processes. By oxidizing a hydrocarbon and proceeding with the partial oxidation reaction mixture, it is possible, using the process of this invention, to obtain the alcohol more'easily, more economically, and in higher yields than would otherwise be possible.

The products obtained according to this invention find various commercial applications. For example, a,a-dimethyl-p-methylbenzyl alcohol is used in the essential oil industry as a perfume base for soaps. This'compound also is an efiicient frothing agent in the flotation of copper, zinc, and lead sulfide ores. u,a-Dimethylbenzyl alcohol has similar commercial applications. 'Thedihydric alcohols such as those derived from diisopropylbenzene also are efficient frothing agents in heavy metal, especially lead sulfide, ore flotations. All of the alcohols aregood wetting-out agents. 7

What I claim and desire to protect by Letters Patent is:

1. The process which comprises treating a mixture containing a hydrocarbon of the formula RH and a hydroperoxide of the formula ROOH with an alkali metal alkoxide under anhydrous conditions at a temperature between about 60 C. and about 200 C. to produce an alcohol of the formula ROH as a major product, the R in said formulas being a radical of the formula where R and R2 represent alkyl groups andArrepresents a radical of the group consisting of aryl and substituted aryl radicals.

2.. The process which comprises treating a mixturecontaininga hydrocarbon of the formula RH an a hydro peroxide of the formula RQQH with .asodium :mcthylate under anhydrous conditions ;at a temperature between about 60 C. and about 200 C. to produce an alcohol of 2,724,729 6 the formula ROH as a major product, the R in said to produce a,u-dirnethylbenzy1 alcohol as the major prodformulas being a radical of the formula uct.

R1 4. The process which comprises treating a mixture con- L taining cumene and a,m-dimethylbenzyl hydroperoxide f 5 with sodium methylate under anhydrous conditions at a R2 temperature between about 80 C. and about 110 C.

where R1 and R2 represent alkyl groups and Ar represents [0 Produce ma-dimethylbenlyl 31601101 as the major P a radical of the group consisting of aryl and substituted aryl radicals.

3. The process which comprises treating a mixture con- 10 taining cumene and a,a-dirnethy1benzy1 hydroperoxide with sodium methylate under anhydrous conditions at a temperature between about 60 C. and about 20') C.

References Cited in the file of this patent Kharasch et al., Jour. Organic Chemistry, vol. 16 (Jan. 1951), 113-127 (15 pages). 

1. THE PROCESS WHICH COMPRISES TREATING A MIXTURE CONTAINING A HYDROCARBON OF THE FORMULA RH AND A HYDROPEROXIDE OF THE FORMULA ROOH WITH AN ALKALI METAL ALKOXIDE UNDER ANHYDROUS CONDITIONS AT A TEMPERATURE BETWEEN ABOUT 60*C. AND ABOUT 200*C. TO PRODUCE AN ALCOHOL OF THE FORMULA ROH AS A MAJOR PRODUCT, THE R IN SAID FORMULAS BEING A RADICAL OF THE FORMULA 